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In Angular 8 I was able to create base components (classes the actual component inhert from) with an "@Injectable" attribute. The Angular 9 compiler tells me:
The component YourComponent inherits its constructor from BaseComponent, but the latter does not have an Angular decorator of its own. Dependency injection will not be able to resolve the parameters of BaseComponent's constructor. Either add a @Directive decorator to BaseComponent, or add an explicit constructor to RoleSelectDialogComponent.
What is the Angular 9 way of doing these things now? This works but looks somehow hacky:
@Component({
selector: 'baseComponent',
template: 'no-ui'
})
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The @Injectable() decorator defines a class as a service in Angular and allows Angular to inject it into a component as a dependency. Likewise, the @Injectable() decorator indicates that a component, class, pipe, or NgModule has a dependency on a service. The injector is the main mechanism.
No. The @Injectable() decorator is not strictly required if the class has other Angular decorators on it or does not have any dependencies. But the important thing here is any class that is going to be injected with Angular is decorated.
providedInlinkDetermines which injectors will provide the injectable.
The first step is to add the @Injectable decorator to show that the class can be injected. The next step is to make it available in the DI by providing it. A dependency can be provided in multiple places: At the Component level, using the providers field of the @Component decorator.
The clue is in the message
Either add a @Directive decorator to BaseComponent
Adding a @Directive() to it should do the trick.
I'm just going through an upgrade now, and my base component automatically has the @Directive() decorator added.
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